Sapphire or corundum is a crystalline form of aluminum oxide and may be found or made in a variety of different colors and shapes. In general, sapphire is a hard and strong material and may be capable of scratching nearly all other materials. Because of its hardness and strength, sapphire may be an attractive alternative to other translucent materials like glass or polycarbonate. However, using some traditional techniques generally makes it difficult to manufacture thin sheets of sapphire material having both a desired strength and optical quality.